Prior art hard disk drive users have problems, which are not easily solved. One problem facing many computer users has to do with the need to use the capabilities of more than one operating system. For example, a user may develop simulations using Linux or BSD Unix, but run spreadsheets, word processors, and presentation development software under some version of Windows. Typically, this requires two computers, because almost all operating systems demand ownership of the boot disk drive. However, there is exactly one hard disk drive in a personal computer that is looked at first upon booting up the computer. What is needed is a way to boot more than one operating system from the same hard disk drive.